This invention relates to tape winding machines and, more particularly, to a tape winding machine for winding a tape on a formed coil used for a rotary electric machine.
A conventional tape winding machine for formed coils (hereinafter referred to merely as "coils"), which comprises a coil support unit as shown in FIGS. 2 and 3 and a tape winding unit is shown in FIG. 7.
A coil A on which a tape is to be wound is shown in FIG. 1. It has parallel longitudinal sections A1 and end sections A2 connecting the respective opposite ends of the longitudinal sections A1 with each having a central twisted portion or loop portion E making a desired angle with a plane defined by the longitudinal sections A1. The inner ends of the opposite loop portions E are spaced apart at a distance L as shown in FIG. 1.
FIGS. 2 and 3 are respectively a plan view and a sectional view showing a main portion of the left side part of the coil support unit. The left and right parts of the coil support units are in a mirror image relationship to each other. A pair of parallel horizontal guide bars 6 are supported at the opposite ends in supports 5. The guide bars 6 penetrate and carry a pair of sliders 7. Each slider 7 can be fixed in a desired position to the guide bars 6 by a set screw 8. The slider 7 is formed with a spherical bearing hole 7a and a slit 7b continuous with the spherical bearing hole 7a. A spherical bearing 3 carrying a clamp 4 is received in the spherical bearing hole 7a. A tightening screw 2 is provided in the slider 7 to penetrate the slit 7b at right angles thereto. The orientation of the clamp 4 with respect to the slider 7 can be adjusted by the clamp screw 2. The clamp 4 can hold the corresponding end section A2 of the coil A, other than the loop portion E between a coil support portion 4a and a clamp member 1a, said coil support portions 4a extending at right angles to the shaft of the bearing 3, and said clamp member 1a being formed at the end of a clamp screw 1 screwed to the clamp 4. After the coil A has been held in a desired position by the clamps 4, a taping ring C, which surrounds a longitudinal section A1 of the coil A, is rotated in the direction of arrow C1 in FIG. 3, whereby a rolled tape B carried by the ring C is unwound and wound on the longitudinal section A1 of the coil A.
With this coil support unit U, the clamp 4 can be adjusted in three dimensions. However, it is difficult to fix the clamp 4 at a desired position with perfect accuracy. In addition, the positioning of the clamp 4 takes a long time. Further, the end section A2 of the coil A is not clamped at a fixed position by the clamp 4. Therefore, tape winding errors are likely to occur, reducing the quality of the product coil. Further, the coil A is supported by the clamp 4 at that portion of the end section A2 which is remote from the longitudinal section A1 on which the tape B is being wound. That is, there is a considerable distance from the portion of the coil A clamped by the clamp 4 to the center of the roll of tape B. Therefore, when the tape winding speed is increased, the force exerted on the coil A is increased to such an extent that the coil A can no longer be supported by the clamp 4. In addition, if the sectional area of the coil A is too small, it is possible that the coil A cannot withstand the taping force.
The tape winding head V shown in FIG. 7 has a housing 9 secured to a support 10. In the housing 9, a taping ring C having an external gear Cl and a horizontal notch C2 is rotatably disposed. A driving force from a motor 11 provided in the housing 9 is coupled through an external gear 12 secured to the shaft of a motor in the housing 9 and through intermediate gears 13 and 14 to the taping ring C to rotate the taping ring C in the direction of arrow D. A tape reel 15 on which an electrically insulating tape B is wound is rotatably mounted on one end side of the taping ring C. As the taping ring C is rotated in the direction of arrow D, the tape B is unwound from the tape reel 15 through a guide roller 16 mounted on one end side of the ring C to be wound on a longitudinal section A1 of the coil A extending along the axis of rotation of the ring C. In the taping operation, the coil A is manually fed at a suitable speed in one direction parallel to the axis of rotation of the taping ring C so that tape B is wound on the longitudinal section A1 of the coil A with a suitable lap as shown in FIG. 2.
The tape winding method using this tape winding unit, however, has the following drawbacks.
(1) Since the coil is manually fed, the feed rate of the tape is not constant, and the width of the lap of tape varies.
(2) Insufficient width of the tape lap causes a lower coil dielectric strength, which is apt to lead to defective coils. Therefore, the operator tries to provide a somewhat greater lap of tape than is necessary, so that a greater quantity of tape than the predetermined quantity is used.
(3) The manual feed of the coil requires considerable skill. The width of the tape lap differs from operator to operator.
(4) Since the operator must move a heavy coil which is under a considerable amount of tension from the tape in the taping operation, he will become tired very easily.